1. Field of the Invention
The present invention relates to a computer peripheral device, especially to a computer peripheral device having a connecting interface of universal serial bus.
2. Description of Related Art
For the connecting interfaces of electronic devices nowadays, universal serial bus, USB in short, has gradually become an important standard. A computer peripheral device can be connected to a computer through a USB connector as an input or output interface. USB interfaces are widely adopted in not only various information and communication products such as personal computers and portable electronic devices but also home appliances, multimedia products and game consoles, etc.
A USB connector is small in form factor and suitable for various kinds of electronic devices. Besides data transmission and reception, power can also be supplied through the USB connector, which brings about much convenience in our lives like at the time to charge batteries. Various types of USB connectors are available such as TYPE-A, TYPE-B, MICRO-USB and MINI-USB, which facilitates extension of the application.
Besides, the USB connector also has fabulous performance on data transmission speed. The maximal data transmission speed of the prior standard USB 1.1 is 12 Mbps (Mega-bit per second) and was enhanced to 480 Mbps for USB 2.0. The state-of-the-art USB 3.0 further boosts the speed to 5 Gbps (Giga-bit per second).
New USB 3.0 is designed to be backward compatible with USB 2.0 and 1.1 and to support the full-duplex mode that has much larger transmission speed than and is absent in USB 2.0 in half-duplex mode. Besides, five more pins, SSRX+, SSRX−, SSTX+, SSTX− and GND_DRAIN are used in USB 3.0 compared with USB 2.0, among which SSRX+ and SSRX− are data input pins, while SSTX+ and SSTX− are data output pins. These pins are located in parallel with the original four pins of USB 2.0, which are VBUS, GND, D+ and D−. The transmission speed of USB 3.0 can be as high as 25 Gbps in case of fiber communication.
In terms of power supply between computers and electronic devices, USB 3.0 can provide a maximal current of 900 mA (only 500 mA for USB 2.0) and adopts multi-level power management technique which can provide various power management plans for various facilities.
However, although USB 3.0 is backward compatible with some earlier USB standards such as USB 2.0 or 1.1 that are currently more common in the marketplace, the USB standard has to be determined in advance in order to provide adequate support for the peripheral device and the computer. In prior art, the determination of the USB standard is performed by a USB 3.0 host controller electrically disposed on a mainboard of the computer system. Since a peripheral device with USB 3.0 connectors is often connected to a computer system with USB 2.0 connectors, the former will not be identified by the computer or will be driven complying with USB 2.0 if a USB 3.0 host controller is missing in the computer system. As a result, the peripheral device with USB 3.0 ports cannot run in an optimized way. For example, a longer battery-charging time and a louder noise upon playing audio may happen to the peripheral device. Even worse, the peripheral device may break down under this condition.
As a result, it is impossible for a peripheral device with USB 3.0 interfaces to be adapted to a computer system with other earlier USB standard than 3.0. Lack of the backward compatibility is a serious limitation in the usage of the USB 3.0 interfaces. However, if a USB 3.0 host controller is added to the computer system with the interface of any earlier USB standard as a common solution to the aforementioned problems, the manufacturing cost will be much higher, which is undesirable in practice.